The invention relates to a diagnostic radiology system for angiographic x-ray examinations, comprising an image intensifier television chain and an image subtraction device connected thereto with two image memories in which, controlled by a control device, image data occurring at different times can be stored and with which a subtracter for the subtraction of the memory contents is connected, as well as comprising a display device for displaying the subtraction images. The display device contains a hard copy installation for documentation purposes. This hard copy installation permits the recording of a series of subtraction images in an on-line operation.
A diagnostic radiology system of this type is described in the German patent application P 31 22 098.3. In the case of this diagnostic radiology system, it is possible, in the first image memory, to store an x-ray image or several integrated x-ray images which correspond to a blank image of the radiography subject, and to store in the second image memory an x-ray image, or several integrated x-ray images which correspond to the same region of the radiography subject, where, however, an x-ray contrast medium has been introduced in the blood vessels. The subtracter forms the difference between the stored images, so that the thus-formed difference image shows only the blood vessels important for the diagnosis which are filled with contrast medium.
For the examination it is important to conduct the storage of the blank image, if possible, at the moment of the just-increasing contrast medium concentration of the subject to be examined. However, this time is difficult to locate, for one can observe the course (or progression) of the contrast medium concentration, in the case of the known diagnostic radiology systems, only when the blank image is already stored, because only then is a subtraction image displayed.